MalwarePublished 7 Aug 2026Updated 11 Aug 2026

postcss-theme-provider (npm) · Malicious Code

Affects postcss-theme-providerSource GCVE Database

Malicious package : remove postcss-theme-provider and rotate any secrets on hosts that installed it.

Data as of 26 Oct 2026, 16:15 UTC

Classification

Malicious package

Published to npm · OSV MAL-2026-13518

What to do

Remove postcss-theme-provider from every project, lockfile and image that pulls it in. Treat any host that installed it as compromised: rotate the credentials, tokens and keys it could read, from a clean machine.

Affected software

Product	Affected	Fixed in
npmpostcss-theme-provider	Affected 1.0.1 – 1.0.4 4 affected builds	Fixed in–

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Description

The postcss-theme-provider npm package version 1.0.2 contains malicious code that executes upon requiring the package. This code queries public Ethereum RPC endpoints for a transaction from a hardcoded attacker wallet, extracts IP addresses from the transaction data, fetches XOR-encrypted JavaScript payloads from these IPs, decrypts and evaluates them, and then spawns a detached Node.js process to run the payload. The malicious code uses Unicode escapes to obfuscate critical strings such as module names and method calls. The attacker can rotate the command-and-control server by posting new Ethereum transactions, enabling dynamic payload updates.

Impact

This malicious package executes arbitrary JavaScript code fetched from attacker-controlled servers every time it is imported, enabling remote code execution on the host system. The attacker can dynamically update the payload by changing the Ethereum transaction data, potentially leading to persistent and stealthy compromise of systems using this package. The use of eval and spawning detached Node.js processes increases the risk of executing arbitrary commands and code, which can lead to full system compromise or further malicious activities.

Defensive guidance

Users should immediately stop using postcss-theme-provider version 1.0.2 and remove it from their projects. Verify dependencies for this package and replace it with a trusted alternative. Monitor for any unexpected child processes or network connections to suspicious IP addresses. Since the malicious code is embedded in the package itself, remediation requires removing the compromised package version.

Summary

The postcss-theme-provider package version 1.0.2 includes a top-level asynchronous immediately-invoked function expression (IIFE) that runs on package import. It contacts public Ethereum RPC endpoints to retrieve the latest transaction from a specific attacker-controlled wallet. From this transaction, it decodes two IPv4 addresses embedded in the 'to' field bytes. It then fetches XOR-encrypted JavaScript payloads from these IP addresses over HTTPS, decrypts the payloads, and executes them using eval. Additionally, it spawns a detached Node.js child process to run the decrypted payload. The code is obfuscated using Unicode escape sequences to hide critical strings such as 'require', 'child_process.spawn', and the attacker wallet address. This Ethereum-based dead-drop mechanism allows the attacker to dynamically update the payload host by posting new transactions, making the malicious payload dynamically controlled and rotated.

References

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What to do

Affected software

Description

AI analysisMachine-generated, updated 7 Aug 2026, 15:49 UTC

Technical details

References

Community reviews